I have Galaxy Nexus and have been trying to get Calibre to see my device. I have my plug in for Android device enabled and doing the debug it says no device is available. I have been sideloading books to Mantano reader on the gnex, but I would love to get Calibre to see the device.

Calibre won't see your Galaxy Nexus because the Galaxy Nexus doesn't appear as a disk drive (i.e. there is no drive letter when you look at the GN in Windows Explorer. The GN uses a newer, more sophisticated communications protocol called Media Transfer Protocol, which according to Microsoft is the best thing since sliced bread but has broken the vast majority of file synchronization products.

There is an immediate solution, and it's a good one that lots of us in the Calibre threads are using. Check out the threads on Calibre Companion. Note that the product is still in it's early stages, but the authors are very active in the threads and have been very responsive to user suggestions and bug reports. It's already a very useful solution.

For a long-term solution, word is that Kovid Goyal is working on adding native MTP support to calibre, but he always has LOTS of stuff on his plate so I wouldn't hold my breath looking for this particular feature in the immediate future. If you can wait a while, you might see what turns up, but otherwise Calibre Companion is $3 well spent.

Calibre Companion is great (just got it myself), but before I found the app I was using the "Connect To Folder" option under the Connect and Share tab on Calibre. I created a folder titled "Temp Ebooks" (you can name it whatever you want) in "My Documents" in Windows 7 and then sent whatever books I wanted on my device to that folder. I then copied and pasted the folder onto my Nexus 7 internal SD. Worked like a charm, and all the books were in folders by author.

before I found the app I was using the "Connect To Folder" option under the Connect and Share tab on Calibre. I created a folder titled "Temp Ebooks" (you can name it whatever you want) in "My Documents" in Windows 7 and then sent whatever books I wanted on my device to that folder. I then copied and pasted the folder onto my Nexus 7 internal SD.

Excellent work around for Android devices that are not assigned USB drive letters.